CLDR-11155 Separate Volume_Metric and Volume_Other

-Remove redundant parameter in PathHeader constructor, reducing from 9 to 8 (still excessive)

-New subroutines makePathHeader and getVolumePageId

-Change example in Dashboard.java from Volume to Area

-Comments

tools/cldr-code/src/main/java/org/unicode/cldr/util/PathHeader.java

@@ -781,7 +781,7 @@ private PathHeader makePathHeader(RawData data, String path, String alt) {
         }
 
         private static Set<UnitConverter.UnitSystem> METRIC =
-            Set.of(UnitConverter.UnitSystem.metric, UnitConverter.UnitSystem.metric_adjacent);
+                Set.of(UnitConverter.UnitSystem.metric, UnitConverter.UnitSystem.metric_adjacent);
 
         private PageId getVolumePageId(String path) {
             // Extract the unit from the path. For example, if path is